Aerion, the U.S. company seeking to attract risk-sharing partners for a proposed supersonic business jet, has announced a number of design changes that it said are necessary to achieve weight and performance targets. The Mach 1.8 airplane’s forward fuselage has been reshaped to provide a slightly raised cockpit, larger cabin and reduced drag. Cabin height and width have grown slightly, as has the width of the cabin floor. The tail has been stretched substantially, a design change that Aerion said will improve takeoff performance and reduce overall weight and cruise drag. The change adds 13 feet to the airplane’s length, which now measures 148 feet.

Aerion also announced that Pratt & Whitney has completed a reliability study of the JT8D-219 engines that would power the airplane. Aerion designers have refined the engine inlets and nozzles to improve performance and reduce noise. The airplane is expected to meet Stage 4/Chapter 4 noise requirements without difficulty, the company said.